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Average age of A and B is 30 years, that...

Average age of A and B is 30 years, that of B and C is 32 years and the average age of C and A is 34 years. The age of C is

A

a. 33 years

B

b. 34 years

C

c. 35 years

D

d. 36 years

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The correct Answer is:
To find the age of C based on the given average ages of A, B, and C, we can follow these steps: ### Step 1: Set up the equations based on the averages given in the question. 1. The average age of A and B is 30 years: \[ \frac{A + B}{2} = 30 \implies A + B = 60 \quad \text{(Equation 1)} \] 2. The average age of B and C is 32 years: \[ \frac{B + C}{2} = 32 \implies B + C = 64 \quad \text{(Equation 2)} \] 3. The average age of C and A is 34 years: \[ \frac{C + A}{2} = 34 \implies C + A = 68 \quad \text{(Equation 3)} \] ### Step 2: Express B in terms of A using Equation 1. From Equation 1: \[ B = 60 - A \quad \text{(Equation 4)} \] ### Step 3: Substitute Equation 4 into Equation 2. Substituting \(B\) from Equation 4 into Equation 2: \[ (60 - A) + C = 64 \] This simplifies to: \[ C - A = 64 - 60 \implies C - A = 4 \implies C = A + 4 \quad \text{(Equation 5)} \] ### Step 4: Substitute Equation 5 into Equation 3. Now substitute \(C\) from Equation 5 into Equation 3: \[ (A + 4) + A = 68 \] This simplifies to: \[ 2A + 4 = 68 \] Subtract 4 from both sides: \[ 2A = 64 \implies A = 32 \] ### Step 5: Find the age of C using Equation 5. Now substitute \(A\) back into Equation 5 to find \(C\): \[ C = A + 4 = 32 + 4 = 36 \] ### Conclusion The age of C is: \[ \boxed{36} \text{ years} \] ---
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